Topflite giant scale P47 Jug

[Paul Williams]

 

First of all a very happy new year to all.

I am normally well on with the winter build buy this time but her indoors demanded the conservatory for xmas parties and I could not face to pack up once started, the garage is far to cold for my old bones so the instruction book for this kit has been read numerous times before the balsa was touched.

Here is what it should look like when finished

 

This is the bubble canopy version I intend to build the razor back more on that

later.

 

[Paul Williams]

 

I thought long and hard about the power plant Topflite recommend 40cc-70cc petrol or same power glow, I really fancied a radial but the budget would not stretch that far so a 65cc RCGK from Al's hobbies was ordered.

The 50cc RCGK used in my Corsair has proved reliable to date so at £170 its worth a risk I purchased a Pitts muffler for a further £50 and all arrived in two days. The spec is;

Bore: 48mm

Capacity: 65cc

Carburettor: Walbro

Engine Type: 2-Stroke Petrol Engine

Max. HP: 5.5hp/4.1KW

Propeller Range: 22x10, 21x10, 22x12 (2 blade)

RPM Range: 1500-8200 RPM

Stroke: 36mm

Weight: 1835g/2097g (Exc/Inc Ignition + Muffler)

 

[Paul Williams]

 

Now then one thing I have to mention is if anyone is thinking of this be warned the retracts are produced uniquely for this model Robart manufacture them and they will set you back over £400 for the full set up.

 

[Paul Williams]

 

So say hi to Bradley who will not be allowed into the conservatory because he loves balsa wood.

On with it then.

To be honest when I opened the box I thought christ what have I done, I spent the first morning going through all the die cut parts and marking them up It may seem a waste of time but it really helped me get a mental picture of what goes where.

The first section to build was the stab

I have to say I love the method Topflite employ having tabs on the under side of the ribs, It saves having to protect the plan from glue damage as the build is done over the plan rarther than on it.

After the top side is complete and sheeted they supply die cut jigs to lay the stab on whilst the other side is sheeted. The balsa blocks supplied for the tips are already cut to the correct radius

 

[Paul Williams]

However thinning down the tips was another story, I tried a razor plane but it just ripped and refused to cut the balsa. It was like cutting cross grain.
In the end I just used a sanding block and swore a lot. I will take  advice gratefully.

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The fin and rudder are more of the same

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[David Ashby - Moderator]

Watching with interest Paul - that's a big box of balsa!

[Kevin Fairgrieve]

Watching.

[Richard Wood]

Hi Paul,

Regarding your problem with the razor plane ripping the balsa -

have you tried going at it in the opposite direction?(still 'with' the grain

of course)

I've had this ripping thing happen before & find this can sometimes

work, along with holding the plane at a steeper angle & reducing

the cut a tad.

There's a lot of timber in that box - good luck with the build,will be

watching with interest.

 

 

[Paul Williams]

 

thanks for the tip Richard I did try all directions, I am convinced its the wood maybe its from the centre of the tree or some thing daft, anyway onwards.

Ok clear of the board and on with more taxing aspects. It was not untill I laid out the main stringers I started to get an idea just how big this was going to be. I placed a six inch rule on the plan here to help you see.
>>

 

The stringers are quite beefy so to help make the curves they mill a 1/4 slot part way through and you fill this with balsa strip after its pinned. Simples
add a few formers, tank support and cockpit deck and very quickly it starts to take shape>>

At this stage you need to make your mind up as to bubble canopy or razor back version

>

I love the look of the razor back and for the extra work involved its my choice so order canopy and press on.>>

Being careful to add the correct formers butt join and add stringers>>

>

[Paul Williams]

Once completed we can start the sheeting, This is the first model I have built that will be 100% sheeted, So I am nervous at this stage and plan to take my time please bear with me. The first taxing piece I came to was having to shape the sheet around the LE of the stab.

After numerous attempts to make a card template I gave up and went for a walk round B&Q for inspiration and presto in the tiling section I found a shaping template tool. Its got to be worth a tenner if it saves the frustration.

Simply push it over the profile then transfer to sheet

Not bad happy days

 

[Paul Williams]

 

Before I carry on I have skipped forward a bit in the instructions and it is evident I will be needing the tail wheel stuff shortly. I phoned Steve Webs and asked for a quote. The main gear £340 and the tail wheel £156 I fell over! No way am I paying that so out with the laptop and start surfing. I ended up on Robart’s site and the prices where much better £199 main gear £99 for retracting tail wheel. Its still hideous but better. I spoke to Webs and asked why I can get them cheaper they reckon its because they purchase through Ripmax or is that Ripoff ! I am tempted to buy a Miller and Lathe but the Mrs went for the rolling pin when I suggested they would fit in the conservatory ha ha. It’s a pain to purchase from America but that’s the way I have gone. The good news is Robard supply a detailed drawing to download so if they have not arrived I can make a template and carry on.

I fitted the Stab onto its saddles this morning, I would have preferred to check the incidence before gluing but there is no ref to the angle either on plan or in the book. I should have an incidence gauge its on my shopping list however I have gambled on the incidence being 0 this being the case a few pins on the centre lines both TE and LE then measure to building board. As it worked out there was less than 1mm difference in the measurement so hopefully 0 deg is where it should be,

This subject of incidence and washout baffled me for ages until I test flew some guys bi-plane he had built. The plane flew awful and I helped sort it for him, the problem was incidence. Have a look at this http://www.robart.com/sites/default/files/How_To_Meter.pdf

Right stab fitted on with the fin, and once again our profile template comes into play

Best thing I ever bought lol

 

 

[Paul Williams]

 

I was not happy with the fin support it’s a butt joint onto the TE of stab I reinforce such joints with cocktail sticks simply drill 2mm hole and standard sticks are a nice tight fit a drop of cyano helps.

Cut off and sand smooth.

The rest was plain sailing but time consuming and at the end of today
here we are

 

[Paul Williams]

I got fed up with balsa so to pass some time I went to play with the new engine.

 

Here we go, will it live

 

[Paul Williams]

 

Ok pushing on the only difficult bit here was folding the sheeting round the fuse but with the help of some glass cleaner here is the end result.

 

 

[Tony Bennett]

thats beutiful

[Stephen Grigg]

Interesting to see what your sticking a motor bike engine into Paul interesting build

[Paul Williams]

The last step is to fill the gaps between stab fin and fuse with carefully shaped balsa sheet, you will notice the rubberised filler which takes up the small gap. This is an important step taken to allow the tail section to flex whilst the powerful 65cc engine pulls the plane upwards vertically. Ok I’m telling porkies I left my glasses at work!

Clear the board and on with the fuse bottom section but before we do here are some stats on this plane.

 

> >

Republic P-47 Razorback Thunderbolt
Type: US escort fighter and fighter-bomber.
History: The Republic P-47 Razorback Thunderbolt was an out­standing fighter, both in the bomber ­ escort and ground-attack roles. It was the largest and heaviest single-engined fighter built during WW2. It was the last in a series of aircraft that began in 1936 with the Seversky P-35 and included the P-43 Lancer in 1940.
Common to all these aircraft was their designer, Alexander Kartveli. In the Republic P-47 Thunderbolt he produced an aircraft that brought the formula to fruition and made up for less successful earlier attempts.
A total of 15,634 Thunderbolts were built in several versions. The 'Razorback, as the first models were called by pilots and ground personnel, was employed intensively by the USAAF and RAF.
After initiating the unlucky P-43 Lancer project, chief Republic designer Kartveli began work in 1939 on two other fighters derived from the Lancer. These were the AP-4 and AP­10. The AP-4 was derived from the P-35 and was powered by a radial engine, while the AP-10 was designed as a light fighter around the liquid­cooled Allison V-12 engine. >>

paradoxically, the massive P-47 Razorback was derived from the lightweight AP-10. For a single-seater the P-47 was a huge aircraft, weighing almost nine tons at take-off. Indeed, when Kartveli submitted the AP-10 design to the USAAC on August 1, 1939, it was rejected and he was asked to develop a larger and more powerful version.

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[Paul Williams]

In November of that year the company signed a contract for two prototypes (the XP-47 and the XP-47 A) to be powered by liquid-cooled Allison engines.
The choice of this powerplant turned out to be a mistake, however. Early combat experience from Europe had made it clear that fighters had to be heavily armed and armoured, as well as offering higher performance. The Allison engine was not powerful enough, nor could it provide satisfactory performance at high altitude. >>

Kartveli therefore developed an alternative project around the most powerful engine then available, the new 2,000 hp Pratt & Whitney Double Wasp radial. He literally designed his aircraft around this large engine and its complex exhaust-gas­powered supercharger, submitting the scheme to the USAAC in June 1940. This time the project, the XP-47B, was accepted without reservations.
A first order for 773 aircraft, worth $56.5 million, was placed while the design was still on the drawing board. Of these, 170 were built as P-47Bs, 602 as P-47Cs and one as the pressurised XP-47E.

The prototype, the XP-47B, took to the air on May 6, 1941, after final adjustments to the engine and super­charger. During flight tests the Thunderbolt showed what it could do, reaching speeds over 410 mph and climbing to 15,000ft within five minutes.
It achieved these results at a take-off weight of almost five and a half tons.
In March 1942 the first production models started coming off the assembly line, and in April 1943 the 56th Fighter Group, attached to the 8th Air Force in Britain, was the first to take the new fighter into combat over Europe.

The P-47 Razorbacks Thunderbolts were successful escorting B=17 and B=24 bombers.

Edited By Paul Williams on 16/01/2011 21:28:24

[Paul Williams]

My first niggle today the control rods would not run smoothly, the holes for the support tubes are pre-drilled in the formers I had to pull a line tight mark off and re-drill the tube support holes. All is well now and no binding is evident. Not much to write up as it was a nice afternoon I spent time with my Warhawk. Still trying to source some 5” wheels for this any ideas? >>

Every now and again in this cheap through away society I get impressed with the quality of certain items, I purchased a duel switch and charging point off ebay it came in two days have a look

All steel no cheap plastic here, brill>>

Ok push on a bit, the control horns are a bit tricky you have to dig out the soft balsa and epoxy in hard wood sections to mount the horns onto. Mmmmm I’m sure they could come up with a better idea. Still job done.

>>

Then I offered it up to mark the horn position RATS I had only fitted it to the wrong side of the rudder. When ever I do anything stupid like this my old fella’s words come to mind “you ain’t made a mistake lad till its on the six o clock news”>>

Making sure this time the two elevator half’s are done.

>

Epoxy the control tubes at both ends and cut flush

>The servo tray is drilled and screwed in position so it can be removed for fuel tank maintenance

Drop in some 12kg torque servos from our friends at Giant Cod and solder the cleeks on the push rods, extending the rudder rod with a soldered coupler.

>

Now the rods are in place I can look towards the front end.

Edited By Paul Williams on 23/01/20

[Paul Williams]

The firewall is lamented with ¼ and 1/8 ply to make up 3/8 they kindly centre punch the centre thrust line for you so mark out engine hole centres from this datum point and fit the captive nuts. I like to dill 2mm hole so they don’t stress the wood to much when you pull them in.>>

Before gluing in the firewall, drill and screw through the sides this holds the wall in place as the epoxy is setting and gives the joint good strength

Before final fitting I will fit the tank and look at throttle links, The tank is massive 32oz it should fly for hours with a petrol engine, the good news here is they supply a petrol bung and tygon tube as well as glow stuff. Nice touch that. Tank as been pressured tested in the sink and that’s enough for today.>>

One of those days when you spend more time thinking than doing, I test fitted the engine and was quite surprised at the distance I needed to make up to bring the prop driver to the right position.

>

At nearly 40mm short it meant the stand offs would have to be 85mm long. I did not fancy that I wanted some solution more robust. I ended up laminating some oak off an old headboard to extend the firewall I have a feeling using the lighter RCGF engine I will need weight up front anyway.

>I cant believe how much time is being eaten up making decisions like where to mount the IGN unit. There’s bags of room within the cowel but will it be effected by heat and oil? The trade off is to fit next to tank but the plug top is moulded on so a massive hole in the firewall would be needed. Grrrrr>

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[Paul Williams]

I took receipt of the scale cockpit kit today and as usual it is a very cheep and flimsy thing for which they charge far to much money (Ripmax again).

 

 

 

Edited By Paul Williams on 17/02/2011 21:36:16

[Paul Williams]

Anyway I’m sure we can beef things up and with a lick of paint it should do the job cosmetically. I read through the instructions and apart from suggesting what colour it should be they are pretty useless. No reference at all on how to fit it to the fuse. Its going to be a make it up job as we go along.

Right cut out cockpit deck

 

Then figure out a way to support the new one the remains of former 4 lends itself to help here.

 

The two sides plus front and rear have good contact areas so can be glued straight on to fuse.

 

I guess how good this is going to be is up to how much time I put into it, here is how it should look

I had read an article about cockpits and how to give the dials some good three dimensional perception. It’s really easy to do you just take some solder wire and wrap round a drill shank (correct dia) run a lace w:st="on">Stanleylace> blade across to make up bevels. Pick up with tweezers and drop some cyano over joint place down on grease paper and carefully push the joint together. Bingo perfect circle, Pick up again and dab some thick cyano on paper dip in place over clock face. Have a look at picture it gives the cockpit face great depth. It only took an hour to do this time well spent I think

 

Ok finished off some cockpit painting

 

[Paul Williams]

Trial fitted and shaped the canopy, I have to say the quality of this is excellent just need to paint in the framework.

I can’t believe how long it took to mask up the canopy

 

I always paint the inside it’s impossible to scratch it afterwards. A little tip, remove masking tape before the paint hardens or the lines will not cut when the tape is pulled, pull back the tape onto itself as photo to get a nice crisp line.

It’s true what they say; about preparation work though I considered hand panting this but with the end result I’m glad I didn’t

 

[Paul Williams]

The retracts turned up today and I have to say it’s true the old cliché you get what you pay for. Brilliant quality there is no movement at all when locked in, the operation is smooth and precise.

So now I can go back to finishing the fuse off. The tail wheel unit dropped in and piped up.

I have reservations about the design here once the sheeting is applied this unit cannot be removed. Its possible to loosen it and get to the steering control arms but should anything happen to the air cylinder it will have to be cut out

Oh well have faith in Robart

Finished sheeting the fuse.

[Paul Williams]

Moving on to the wings, have to say still impressed with the building methods. I have not felt the urge to strengthen or change much up to now. The instructions suggest gluing up the wing skins while the board is free. I find a good method is to trim with straight edge then use the straight edge to hold flat while the edges are slid together have a look at next photo.

I use cyano with this method and as yet have had no misalignments.

Dont forget to put wax paper under joint.

Pretty much normal and plane sailing up to this stage.